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2022 ◽  
Vol 21 (1) ◽  
Author(s):  
Fernando Bracalente ◽  
Martín Sabatini ◽  
Ana Arabolaza ◽  
Hugo Gramajo

Abstract Background A broad diversity of natural and non-natural esters have now been made in bacteria, and in other microorganisms, as a result of original metabolic engineering approaches. However, the fact that the properties of these molecules, and therefore their applications, are largely defined by the structural features of the fatty acid and alcohol moieties, has driven a persistent interest in generating novel structures of these chemicals. Results In this research, we engineered Escherichia coli to synthesize de novo esters composed of multi-methyl-branched-chain fatty acids and short branched-chain alcohols (BCA), from glucose and propionate. A coculture engineering strategy was developed to avoid metabolic burden generated by the reconstitution of long heterologous biosynthetic pathways. The cocultures were composed of two independently optimized E. coli strains, one dedicated to efficiently achieve the biosynthesis and release of the BCA, and the other to synthesize the multi methyl-branched fatty acid and the corresponding multi-methyl-branched esters (MBE) as the final products. Response surface methodology, a cost-efficient multivariate statistical technique, was used to empirical model the BCA-derived MBE production landscape of the coculture and to optimize its productivity. Compared with the monoculture strategy, the utilization of the designed coculture improved the BCA-derived MBE production in 45%. Finally, the coculture was scaled up in a high-cell density fed-batch fermentation in a 2 L bioreactor by fine-tuning the inoculation ratio between the two engineered E. coli strains. Conclusion Previous work revealed that esters containing multiple methyl branches in their molecule present favorable physicochemical properties which are superior to those of linear esters. Here, we have successfully engineered an E. coli strain to broaden the diversity of these molecules by incorporating methyl branches also in the alcohol moiety. The limited production of these esters by a monoculture was considerable improved by a design of a coculture system and its optimization using response surface methodology. The possibility to scale-up this process was confirmed in high-cell density fed-batch fermentations.


BMC Biology ◽  
2022 ◽  
Vol 20 (1) ◽  
Author(s):  
Samantha M. Solon-Biet ◽  
Lucy Griffiths ◽  
Sophie Fosh ◽  
David G. Le Couteur ◽  
Stephen J. Simpson ◽  
...  

Abstract Background The role of dietary branched chain amino acids (BCAAs) and their effect on metabolic health is complex. How dietary BCAA levels and their interaction with background nutrition affect health is unclear. Here, we used meta-analysis and meta-regression, together with the nutritional modelling, to analyse the results of rodent studies that increased the level of dietary BCAAs and measured circulating levels, outcomes related to metabolic health, body mass and food intake. Results Across all studies, increasing dietary BCAAs resulted in increased levels of circulating BCAAs. These effects, however, were heavily moderated by background dietary levels whereby on high BCAA diets, further increases were not reflected in the blood. Impaired glucose tolerance was associated with elevated dietary BCAAs, with the greatest effect occurring with a simultaneous increase in total protein intake. Effects of dietary BCAAs on plasma glucose, insulin, or HOMA emerged only when dietary macronutrient background was considered. We found that elevated dietary BCAAs increases % body fat, with largest increases in adiposity occurring when BCAAs are increased on a high protein, low carbohydrate dietary background. Finally, we found that increased dietary BCAAs were associated with increased food intake when the background diet was low in BCAAs. Conclusion Our data highlights the interaction between BCAAs and background nutrition. We show that the effects of BCAAs on metabolic health cannot be studied in isolation but must be considered as part of complex mixture of dietary components.


2022 ◽  
Vol 11 ◽  
Author(s):  
Xianhui Liu ◽  
Weiyu Zhang ◽  
Huanrui Wang ◽  
Lin Zhu ◽  
Kexin Xu

BackgroundPrevious reports have shown that short/branched chain acyl-CoA dehydrogenase (ACADSB) plays an important role in glioma, but its role in clear cell renal carcinoma (ccRCC) has not been reported.MethodsThe TIMER and UALCAN databases were used for pan-cancer analysis. RNA sequencing and microarray data of patients with ccRCC were downloaded from the Cancer Genome Atlas and Gene Expression Omnibus database. The differential expression of ACADSB in ccRCC and normal kidney tissues was tested. Correlations between ACADSB expression and clinicopathological parameters were assessed using the Wilcoxon test. The influences of ACADSB expression and clinicopathological parameters on overall survival were assessed using Cox proportional hazards models. Gene set enrichment analysis (GSEA) was performed to explore the associated gene sets enriched in different ACADSB expression phenotypes. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed on genes with similar expression patterns to ACADSB. Correlations between ACADSB and ferroptosis-related genes were assessed using Spearman’s correlation analysis.ResultsPan-cancer analysis revealed that ACADSB is down-regulated in multiple cancers, and decreased expression of ACADSB correlates with poor prognosis in certain types of cancer. Differential expression analyses revealed that ACADSB was down-regulated in ccRCC, indicating that ACADSB expression could be a single significant parameter to discriminate between normal and tumor tissues. Clinical association analysis indicated that decreased ACADSB expression was associated with high tumor stage and grade. The Cox regression model indicated that low ACADSB expression was an independent risk factor for the overall survival of patients with ccRCC. GSEA showed that 10 gene sets, including fatty acid (FA) metabolism, were differentially enriched in the ACADSB high expression phenotype. GO and KEGG pathway enrichment analysis revealed that ACADSB-related genes were significantly enriched in categories related to FA metabolism, branched-chain amino acid (BCAA) metabolism, and iron regulation. Spearman’s correlation analysis suggested that the expression of ACADSB was positively correlated with the expression of ferroptosis driver genes.ConclusionsACADSB showed good diagnostic and prognostic abilities for ccRCC. The downregulation of ACADSB might promote tumorigenesis and tumor progression by inhibiting FA catabolism, BCAA catabolism, and ferroptosis in ccRCC.


2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Yanfei Zhang ◽  
Jeremy D. Cortez ◽  
Sarah K. Hammer ◽  
César Carrasco-López ◽  
Sergio Á. García Echauri ◽  
...  

AbstractBranched-chain amino acid (BCAA) metabolism fulfills numerous physiological roles and can be harnessed to produce valuable chemicals. However, the lack of eukaryotic biosensors specific for BCAA-derived products has limited the ability to develop high-throughput screens for strain engineering and metabolic studies. Here, we harness the transcriptional regulator Leu3p from Saccharomyces cerevisiae to develop a genetically encoded biosensor for BCAA metabolism. In one configuration, we use the biosensor to monitor yeast production of isobutanol, an alcohol derived from valine degradation. Small modifications allow us to redeploy Leu3p in another biosensor configuration that monitors production of the leucine-derived alcohol, isopentanol. These biosensor configurations are effective at isolating high-producing strains and identifying enzymes with enhanced activity from screens for branched-chain higher alcohol (BCHA) biosynthesis in mitochondria as well as cytosol. Furthermore, this biosensor has the potential to assist in metabolic studies involving BCAA pathways, and offers a blueprint to develop biosensors for other products derived from BCAA metabolism.


Author(s):  
Yang Zhang ◽  
Xiao Guo ◽  
Huaiyi Yang ◽  
Shuobo Shi

Fatty acid alkyl esters have broad applications in biofuels, lubricant formulas, paints, coatings, and cosmetics. Traditionally, these esters are mostly produced through unsustainable and energy-intensive processes. In contrast, microbial production of esters from renewable and sustainable feedstocks may provide a promising alternative and has attracted widespread attention in recent years. At present, yeasts are used as ideal hosts for producing such esters, due to their availability for high-density fermentation, resistance to phage infection, and tolerance against toxic inhibitors. Here, we summarize recent development on the biosynthesis of alkyl esters, including fatty acid ethyl esters (FAEEs), fatty acid short-branched chain alkyl esters (FASBEs), and wax esters (WEs) by various yeast cell factories. We focus mainly on the enzyme engineering strategies of critical wax ester synthases, and the pathway engineering strategies employed for the biosynthesis of various ester products. The bottlenecks that limit productivity and their potential solutions are also discussed in this review.


2022 ◽  
Vol 12 ◽  
Author(s):  
Fanny Canon ◽  
Valérie Briard-Bion ◽  
Julien Jardin ◽  
Anne Thierry ◽  
Valérie Gagnaire

Lactic acid bacteria (LAB) are responsible for the sanitary, organoleptic, and health properties of most fermented products. Positive interactions between pairs of LAB strains, based on nitrogen dependencies, were previously demonstrated. In a chemically defined medium, using milk and lupin proteins as sole nitrogen source, two proteolytic strains were able to sustain the growth of non-proteolytic strains, but one did not. The objective of the present study was, thus, to determine which specific peptides were implicated in the positive interactions observed. Peptides produced and involved in the bacterial interactions were quantified using tandem mass spectrometry (LC-MS/MS). About 2,000 different oligopeptides ranging from 6 to more than 50 amino acids in length were identified during the time-course of the experiment. We performed a clustering approach to decipher the differences in peptide production during fermentation by the three proteolytic strains tested. We also performed sequence alignments on parental proteins and identified the cleavage site profiles of the three bacterial strains. Then, we characterized the peptides that were used by the non-proteolytic strains in monocultures. Hydrophobic and branched-chain amino acids within peptides were identified as essential in the interactions. Ultimately, better understanding how LAB can positively interact could be useful in multiple food-related fields, e.g., production of fermented food products with enhanced functional properties, or fermentation of new food matrices.


2022 ◽  
Vol 8 (1) ◽  
Author(s):  
Masako Fujiwara ◽  
Itiro Ando ◽  
You Shishido ◽  
Yutaka Imai ◽  
Hiroyuki Terawaki

Abstract Background Hemodialysis (HD) is a protein catabolic event. However, the amino acid (AA) kinetics during HD sessions involved in protein breakdown have not been well investigated in patients with and without diabetes mellitus (DM). Case presentation Three patients (two patients with DM and one patient without DM) underwent fasting HD. Plasma levels of branched-chain AAs (BCAA; leucine, isoleucine, and valine), major non-essential AAs (alanine and glutamine, including glutamate), insulin, and ketone bodies were measured every hour during each HD session. After the start of the HD session, the plasma levels of insulin and all BCAAs dropped simultaneously. There was a significant subsequent increase in the plasma level of leucine and isoleucine levels, while valine levels remained constant. However, the recovery in levels of BCAAs during HD indicated a profound amount of BCAAs entering the blood from body tissues such as muscles. BCAAs may have surpassed their removal by HD. Ketone body levels increased continuously from the start of the sessions and reached high values in patients with DM. Synchronous changes in insulin depletion and an increase in the levels of ketone bodies may indicate disruption of energy metabolism. Conclusions This is the first report to demonstrate the time course of the changes in circulating levels of BCAAs and related metabolites in energy homeostasis during HD. An increase in BCAA levels during HD was found to be due to their transfer from the body tissue which suggested protein breakdown.


2022 ◽  
Author(s):  
BeiBei GAO ◽  
Qiong SHEN ◽  
Ying WU ◽  
MengDie CAO ◽  
QiWu ZHANG ◽  
...  

Abstract AimsSerum branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs) are associated with obesity, insulin resistance and type 2 diabetes mellitus (T2DM). We want to investigate the levels of these amino acids in women with GDM and subsequently examine their changes in response to an oral glucose tolerance test (OGTT). Methods43 GDMs and 67 non-GDMs during their second trimester were recruited in this study. A 75-g OGTT was administered, and fasting, 1-h, and 2-h blood samples were obtained. Serum BCAA and AAA levels were measured by liquid chromatography-tandem mass spectrometry.ResultsThe differences of BCAAs and AAAs between women with GDM and controls during their second trimester were not evident during fasting, while became significant after a 75-g glucose load. Glucose ingestion decreased the levels of BCAAs and AAAs in both groups. Notably, GDMs showed a delayed and blunted decrease of these amino acids compared to non-GDMs. The risks of 2-h change of BCAAs and AAAs for GDM were significant.ConclusionsWe identified that the differences of BCAAs and AAAs between women with GDM and controls during their second trimester, which were not evident during fasting, could be provoked by performing OGTT.


2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Ahjin Jang ◽  
Dasom Cheon ◽  
Eunha Hwang ◽  
Yangmee Kim

AbstractTo survive in diverse environments, bacteria adapt by changing the composition of their cell membrane fatty acids. Compared with aerobic bacteria, Cutibacterium acnes has much greater contents of branched-chain fatty acids (BCFAs) in the cell membrane, which helps it survive in anaerobic environments. To synthesize BCFAs, C. acnes acyl carrier protein (CaACP) has to transfer growing branched acyl intermediates from its hydrophobic cavity to fatty acid synthases. CaACP contains an unconserved, distinctive Cys50 in its hydrophobic pocket, which corresponds to Leu in other bacterial acyl carrier proteins (ACPs). Herein, we investigated the substrate specificity of CaACP and the importance of Cys50 in its structural stability. We mutated Cys50 to Leu (C50L mutant) and measured the melting temperatures (Tms) of both CaACP and the C50L mutant by performing circular dichroism experiments. The Tm of CaACP was very low (49.6 °C), whereas that of C50L mutant was 55.5 °C. Hydrogen/deuterium exchange experiments revealed that wild-type CaACP showed extremely fast exchange rates within 50 min, whereas amide peaks of the C50L mutant in the heteronuclear single quantum coherence spectrum remained up to 200 min, thereby implying that Cys50 is the key residue contributing to the structural stability of CaACP. We also monitored chemical shift perturbations upon apo to holo, apo to butyryl, and apo to isobutyryl conversion, confirming that CaACP can accommodate isobutyryl BCFAs. These results provide a preliminary understanding into the substrate specificity of CaACPs for the production of BCFAs necessary to maintain cell membrane fluidity under anaerobic environments.


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